Explicit characterization of two classes of regular bent functions

Abstract

This paper considers two classes of p-ary functions studied by Li et al. (IEEE Trans Inf Theory 59(3):1818–1831, 2013). The first class of p-ary functions is of the form $$\begin{aligned} f(x)=Tr^n_1\left( a x^{l(q-1)}+b x^{\left( l+\frac{q+1}{2}\right) (q-1)}\right) +\epsilon x^{\frac{q^2-1}{2}}. \end{aligned}$$ Another class of p-ary functions is of the form $$\begin{aligned} f(x)={\left\{ \begin{array}{ll} \sum ^{q-1}_{i=0} Tr^n_1(a x^{(ri+s)(q-1)})+\epsilon x^{\frac{q^2-1}{2}},&{} x\ne 0,\\ f(0),&{} x=0. \end{array}\right. } \end{aligned}$$ We generalize Li et al.’s results, give necessary conditions for two classes of bent functions, and present more explicit characterization of these regular bent functions for different cases.